On “Luther,” Idris Elba plays a brilliant but troubled “copper,” a detective whose unorthodox methods have placed him under investigation. He’s almost too good at his job and his tenacity has resulted in the death of some of the suspects he’s pursued.

The show, which returns for four consecutive episodes starting Tuesday at 10 p.m., has never shied away from brutality, introducing villains so playful in their cruelty — like one last season who threatened to blow up a bus filled with children — that it risks crossing the line into cartoonish.

This season, though, finds the show veering closer to pure horror.

In the first two episodes, several victims are targeted because of their delicate feet, and their corpses are ghoulishly dressed. The acts of murder will make you cover your eyes, but the director’s masterful use of prolonged silence while you watch the victims go about their lives, tracked by a killer waiting to pounce, will shatter your nerves.

There’s a scene in the season premiere in which a man physically maims himself to avoid implication for a crime. The violent act, like most in the show, is not shown. The moments leading to it, though, are presented in chilling detail, with the viewer sensing what’s to come. We note the man’s misleading sense of calm, as he even pauses to gulp down a grape just seconds before his self-inflicted mayhem. Any blood is shown after the fact. We never see the injury or the violence, although we do hear it, and it’s in these elements — the lead-up, the contemplation, the sound of the action and the messy aftermath — that the show’s horror is brought to bear.

If anyone can handle this nightmarish chaos, it’s Detective John Luther. He can solve a baffling murder, console a devastated dad, hoist a suspect over a railing with the ease of tossing a fast food wrapper in the trash, and still manage to pick up a blond hottie (Sienna Guillory) he meets after their cars collide.

Filmed over four-and-a-half months during a dreary, overcast winter, Elba says the combination of gray skies, cement-colored council estates and red blood left him in need of a psychic recharge.

“Playing this character in the dead of winter makes this a very difficult show to shoot,” says Elba, 40. “It’s grueling. It’s cold, it’s wet, it’s miserable. I’m dealing with a lot of destruction, death, and people’s emotions in ‘Luther.’ So it leaves me with an odd frame of mind.”

To recover, Elba retreats into his love of music. A longtime DJ whose work was featured on Jay Z’s 2007 album “American Gangster,” Elba secured a DJ residence in London as soon as this current season wrapped, then spent the summer spinning in Ibiza.

“DJ’ing was a complete reset for me,” he says. “That was prior to anyone in England seeing this season, so I wasn’t being bothered publicly. People weren’t really chasing me down like what they’re like after the show’s on. So I had this time to just reset myself, play music, and be who I am.”

It’s surprising to hear Elba, named one of People magazine’s Sexiest Men Alive in 2011, say that the public gives him any space at all. His irresistible combination of talent and sex appeal has made “Luther” creator Neal Cross’s job harder.

“In some ways, it’s a challenge that a man that beautiful and charismatic doesn’t have a girlfriend [on the show]. A lot of people who write to us are people who want to help him,” Cross says. “It’s not just people who want to f – – k him; it’s people who want to marry him. We get a lot of old ladies who want to give him a good square meal and do his laundry for him.”

With this kind of fan response, it’s not suprising that Elba is a frequently mentioned candidate for the next James Bond, despite the current Bond, Daniel Craig, having two films left on his contract.

While Elba has dismissed this as rumor (while not denying interest in the role), fans are salivating at the possibility, with a “We Want Idris Elba for James Bond” Facebook page having over 28,000 likes.

But now, Elba, who has an 11-year-old daughter, Isan, from a four-year marriage to makeup artist Kim Elba, has different hype to gear up for — the onslaught of attention sure to come for his Oscar-bait biopic, “Mandela: Long Walk to Freedom,” which will be released Nov. 29.

Regarding the role’s awards buzz, Elba is maintaining a sanity-saving resistance to the ego boost.

“I try to stay away from that talk,” he says. “It’s obviously a compliment to have people think I deserve something like that, but this film is so much more about a man that changed our world. The man’s life deserves that Oscar, not me.”

Given the ever-growing adulation from fans and industry alike, accolades for Elba will surely continue to grow. But the actor demurs for the most part on discussing how being a sex symbol has changed his life. In the past, he has noted that it’s made him “a lot less trusting” with women, telling British paper The Daily Mail that women “don’t want you, they want the fact that you’re famous.”

Seemingly cautious about sounding too egotistical, the actor will admit when pressed that maybe fans are not quite as cavalier about his presence as he first let on.

“I’ll be DJ’ing, and they’ll see me right there. I don’t have any security or anything like that,” he says. “Over the last couple of weeks, there have been a lot of fans that come, which is quite hard to play to, because they just wanna see you smile and talk to them.”